O.K. Thank you for the additional information.
I think that you should probably be evaluated by a physician. These symptoms - of lightheadedness, cold sweats, and a "tension" to your heart (I'm not quite sure what you mean by this) - could be an indicator of some danger. If your heart is not totally healthy, then this could be an early indicator. Similarly, these symptoms can also be an indicator of problems with adequate blood perfusion to the tissues (brain, etc.). So I think that you could be seen.
If these are ruled out and you are determined to be healthy, then this could be related to hydration - it's always important when working out to make sure that you're taking in plenty of water. The old addage of 8 8 oz. glasses of water a day is probably not adequate here, so you should strive for more. In addition, you need to get adequate nutrition, as well, and this includes a well-balanced diet as well as making sure that you're getting all of the vitamins and minerals that you need. A multivitamin can help (you should always add Calcium as well), as well as mineral supplementation if you're sweating a lot. So these could also be contributing.
Finally, as someone who has exercised myself a lot in the past, and had to come back to it after a break, it can be tough to do so, and it can be a strain. In this regard, it's always good to take it very slow.
So call your physician, and get evaluated. And if need be, and you can't get in to see your physician, then head to the emergency room. And if your symptoms worsen, then get into see someone right away.
I hope this helps. Please let me know if you have any further questions - I'm more than happy to try and help.
Take care - Dr. Fay
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